Evaluation of the Toxic Activity of the Graphene Oxide in the Ex Vivo Model of Human PBMC Infection with Mycobacterium tuberculosis.

Graphene Oxide has been proposed as a potential adjuvant to develop improved anti-TB treatment, thanks to its activity in entrapping mycobacteria in the extracellular compartment limiting their entry in macrophages. Indeed, when administered together with linezolid, Graphene Oxide significantly enhanced bacterial killing due to the increased production of Reactive Oxygen Species. In this work, we evaluated Graphene Oxide toxicity and its anti-mycobacterial activity on human peripheral blood mononuclear cells. Our data show that Graphene Oxide, different to what is observed in macrophages, does not support the clearance of Mycobacterium tuberculosis in human immune primary cells, probably due to the toxic effects of the nano-material on monocytes and CD4+ lymphocytes, which we measured by cytometry. These findings highlight the need to test GO and other carbon-based nanomaterials in relevant in vitro models to assess the cytotoxic activity while measuring antimicrobial potential.

Are We Ready for Nosocomial Candida auris Infections? Rapid Identification and Antifungal Resistance Detection Using MALDI-TOF Mass Spectrometry May Be the Answer.

The occurrence of multidrug-resistant Candida auris isolates and the increased mortality associated with invasive infections or outbreaks due to this Candida species have been reported in many healthcare settings. Therefore, accurate and rapid identification at the species level of clinical C. auris isolates as well as their timely differentiation as susceptible or resistant to antifungal drugs is mandatory. Aims of the present study were to implement the MALDI-TOF mass spectrometry (MS) Bruker Daltonics Biotyper® database with C. auris spectrum profiles and to develop a fast and reproducible MS assay for detecting anidulafungin (AFG) resistance in C. auris isolates. After creation of main C. auris spectra, a score-oriented dendrogram was generated from hierarchical cluster analysis, including spectra of isolates from C. auris and other Candida (C. glabrata, C. guilliermondii, C. haemulonii, C. lusitaniae, and C. parapsilosis) or non-Candida (Rhodotorula glutinis) species. Cluster analysis allowed to group and classify the isolates according to their species designation. Then, a three-hour incubation antifungal susceptibility testing (AFST) assay was developed. Spectra obtained at null, intermediate, or maximum AFG concentrations were used to create composite correlation index matrices for eighteen C. auris isolates included in the study. All six resistant C. auris isolates were detected as resistant whereas 11 of 12 susceptible C. auris isolates were detected as susceptible by the MS-AFST assay. In conclusion, our MS-based assay offers the possibility of rapidly diagnosing and appropriately treating patients with C. auris infection.

PE_PGRS3 ensures provision of the vital phospholipids cardiolipin and phosphatidylinositols by promoting the interaction between M. tuberculosis and host cells.

PE_PGRS proteins of Mycobacterium tuberculosis (Mtb) constitute a large family of complex modular proteins whose role is still unclear. Among those, we have previously shown, using the heterologous expression in Mycobacterium smegmatis, that PE_PGRS3 containing a unique arginine-rich C-terminal domain, promotes adhesion to host cells. In this study, we investigate the role of PE_PGRS3 and its C-terminal domain directly in Mtb using functional deletion mutants. The results obtained here show that PE_PGRS3 is localized on the mycobacterial cell wall and its arginine-rich C-terminal region protrudes from the mycobacterial membrane and mediates Mtb entry into epithelial cells. Most importantly, this positively charged helical domain specifically binds phosphorylated phosphatidylinositols and cardiolipin, whereas it is unable to bind other phospholipids. Interestingly, administration of cardiolipin and phosphatidylinositol but no other phospholipids was able to turn-off expression of pe_pgrs3 activated by phosphate starvation conditions. These findings suggest that PE_PGRS3 has the key role to serve as a bridge between mycobacteria and host cells by interacting with specific host phospholipids and extracting them from host cells, for their direct integration or as a source of phosphate, during phases of TB pathogenesis when Mtb is short of phosphate supply.

Increased CD95 (Fas) and PD-1 expression in peripheral blood T lymphocytes in COVID-19 patients.

A low count of CD4+ and CD8+ lymphocytes is a hallmark laboratory finding in the coronavirus disease 2019 (COVID-19). Using flow cytometry, we observed significantly higher CD95 (Fas) and PD-1 expression on both CD4+ T and CD8+ T cells in 42 COVID-19 patients when compared to controls. Higher CD95 expression in CD4+ cells correlated with lower CD4+ counts. A higher expression of CD95 in CD4+ and CD8+ lymphocytes correlated with a lower percentage of naive events. Our results might suggest a shift to antigen-activated T cells, expressing molecules increasing their propensity to apoptosis and exhaustion during COVID-19 infection.

Comparative performance evaluation of Wako ß-glucan test and Fungitell assay for the diagnosis of invasive fungal diseases.

The Fungitell assay (FA) and the Wako ß-glucan test (GT) are employed to measure the serum/plasma 1,3-ß-D-glucan (BDG), a well-known invasive fungal disease biomarker. Data to convincingly and/or sufficiently support the GT as a valuable alternative to the FA are yet limited. In this study, we evaluated the FA and the GT to diagnose invasive aspergillosis (IA), invasive candidiasis (IC), and Pneumocystis jirovecii pneumonia (PJP). The FA and GT performances were compared in sera of patients with IA (n = 40), IC (n = 78), and PJP (n = 17) with respect to sera of control patients (n = 187). Using the manufacturer's cutoff values of 80 pg/mL and 11 pg/mL, the sensitivity and specificity for IA diagnosis were 92.5% and 99.5% for the FA and 60.0% and 99.5% for the GT, respectively; for IC diagnosis were 100.0% and 97.3% for the FA and 91.0% and 99.5% for the GT, respectively; for PJP diagnosis were 100.0% and 97.3% for the FA and 88.2% and 99.5% for the GT, respectively. When an optimized cutoff value of 7.0 pg/mL for the GT was used, the sensitivity and specificity were 80.0% and 97.3% for IA diagnosis, 98.7% and 97.3% for IC diagnosis, and 94.1% and 97.3% for PJP diagnosis, respectively. At the 7.0-pg/mL GT cutoff, the agreement between the assays remained and/or became excellent for IA (95.1%), IC (97.3%), and PJP (96.5%), respectively. In conclusion, we show that the GT performed as well as the FA only with a lowered cutoff value for positivity. Further studies are expected to establish the equivalence of the two BDG assays.